Medical image diagnosis has rapidly advanced by X-ray CT (Computed Tomography) apparatuses and MRI (Magnetic Resonance Imaging) apparatuses which have been put to practical use with recent developments in computer technology, and has thereby become indispensable in current medical care. In particular, in the X-ray CT apparatuses and the MRI apparatuses, biological information detecting units, arithmetic processing units or the like have been improved in processing speed and performance, so that image data can be displayed in real time. Furthermore, three-dimensional image information (volume data) can be more easily collected, and three-dimensional image data and MPR (Multi Planar Reconstruction) image data can be more easily generated/displayed by using the volume data. Thus, it becomes possible to accurately detect a stenosis site in a coronary artery of a patient having ischemic heart disease (referred to as object below), and accurately measure a rate of stenosis thereof, for example.
The ischemic heart disease such as myocardial infarction is mainly caused by a stenosis in a coronary artery. Thus, in a conventional case, a stenosis site in a coronary artery is detected and a rate of stenosis thereof is measured by use of morphological image data such as two-dimensional image data and three-dimensional image data obtained by administering a contrast agent into coronary arteries. A stenosis site having a relatively high rate of stenosis among the detected stenosis sites is determined as a cause of myocardial infarction, and subjected to intravascular treatment such as PCI (Percutaneous Coronary Intervention) in which an intravascular device such as a stent is placed in the stenosis site.
However, myocardial infarction may sometimes not develop even when there is a stenosis site in a coronary artery. There has been a report that a patient has a favorable prognosis when given medication therapy as compared to a patient given the PCI depending on a degree of ischemia in myocardial tissue. Thus, evaluation of a stenosis site with respect to an ischemic region in myocardial tissue is considered as important in order to determine a course of treatment for the stenosis site.
In response to such requirements, a medical image diagnosis apparatus or a medical image processing apparatus has been proposed which processes time-series volume data collected from a cardiac region of an object into which a contrast agent is administered, and thereby generates/displays functional image data such as myocardial perfusion image data in which an ischemic region in myocardial tissue can be identified.
Separate collection modes of image data are respectively employed to collect the morphological image data to detect a stenosis site in a coronary artery and measure a rate of stenosis, and to collect the functional image data to identify or measure an ischemic region. Attending doctors of the object subjectively analyze information on the stenosis site and information on the ischemic region obtained in the respective collection modes based on their experiences, and judge a relationship between the ischemic region and the stenosis site.
In recent years, a method of synthesizing an ischemic region in functional image data on morphological image data of a cardiac region including a stenosis site in a coronary artery and displaying the obtained image data has been also developed. In this case, however, the attending doctors also make a subjective judgment based on their experiences by observing the respective image data. With the aforementioned conventional methods, the relationship between the ischemic region and the stenosis site cannot be accurately determined. It is thus difficult to determine a preferable course of treatment for the stenosis site.